Scientists Fool People Into Thinking They're Tiny or Giant

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Fooling the brain so one experiences the world as either doll- or
giant-size a la "Alice in Wonderland" is the latest trick from a
mind-bending cadre of scientists in Sweden.

These findings help reveal how our bodies can influence how we
perceive the world around us, and down the line, could lead to
mind-controlled robotics.

Looking glass

To start with, volunteers lied down wearing video displays on
their heads that made them see the bodies of the mannequins of
various sizes, from about 1 to 13 feet (30 centimeters to 4
meters) tall.

As the volunteers looked down at "their bodies," they saw these
mannequins get repeatedly poked in the leg with a rod; at the
same time, their real bodies got prodded in the same place. This
began the illusion that the body they saw was their own.
[ Eye
Tricks: Gallery of Visual Illusions ]

If real people then wandered into view when volunteers saw
themselves as having miniature bodies, "even though we know just
how large people are, the illusion makes us perceive other people
as giants — it's a very weird experience," said researcher Henrik
Ehrsson, a cognitive neuroscientist at the Karolinska Institute
in Sweden who tried the experiment on himself. [ Video
of body-swapping experiment ]

"The illusion is very strong," researcher Björn van der Hoort, a
cognitive neuroscientist at the Karolinska Institute in Sweden,
told LiveScience. "People know they are not the doll, but it
feels like it. It is a
sensory illusion. Everybody feels the illusion, and of course
we did the experiments on ourselves. It is a crazy and funny
phenomenon to be a small Barbie doll being touched by a gigantic
hand that is bigger than your own body."

This research explores theories of how we understand our
surroundings. The conventional view is that we perceive size and
distance by interpreting different visual cues, such as the
apparent size of an object and how it moves. However, this work
shows that how large or small we feel we are can have a profound
effect as well, with the body serving as a fundamental reference
point that affects our perceptions.

When volunteers experienced tiny bodies as their own, they
perceived themselves as living in a giant world, perceiving
objects in view as larger and farther away than in reality. On
the other hand, when participants had giant-sized illusions, they
perceived objects as smaller and nearer.

"The most exciting part is the flexibility of the brain regarding
ownership of a body," van der Hoort said. "Theoretically, there
is no limit in size of that artificial body."

"Robots are helpful in places where humans can not go — for
example, to repair a leaking oil pipe deep under sea, or to
repair a nuclear power plant if there is too much radiation, or
doing micro-surgery inside a patient's body," van der Hoort said.
"Until now, robots were controlled by levers and buttons, much
like a computer game, but our findings show that one can feel
[like they are] the robot, which would make the control much more
intuitively and more efficient."

He cautioned, however, "there is still a big gap between theory
and practice, and it is hard to predict a time schedule, but we
think that in 10 to 15 years it should be possible to do this."

The scientists detailed their findings May 25 in the journal PLoS
ONE.

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